This could be an airleak after the airflow meter, any freshen dragged in here isn t seen by the ECU and therefore not compensated for and can lean the engine out and can after that permit the engine to rev stirring when not desired causing prickly running. As its a mechanical oddity it tends not to slope upon the irregularity vivacious and you can sometimes hear a hissing noise considering the engine running.
Its in addition to worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a sick pump will every upshot in insufficient fuel mammal delivered to the engine. Might as a consequence be worth cleaning out the idle eagerness manage motor / valve as these acquire clogged taking place later carbon and some brake cleaner washed through helps clear things off.
have you looked into throttle body coking and/or combustion chamber/valve carbon buildup? are you up to date upon every maintenance; spark plugs fuel filter pcv vlave etc? have you performed a visual inspection and listened to engine as it warms occurring and is warmed up? oftentimes in engine feat many factors may cause the thesame symptom(s)